Conventional image processing devices etc. carry out a process for sharpening an image (hereinafter referred to as sharpening process) in order to improve image quality of the image. For example, conventional television receivers carry out contour compensation for steepening rising and falling of an image signal corresponding to a contour portion of an image to be displayed by the television receivers. The contour compensation is carried out in such a manner that a high frequency component of an image signal (luminance signal) inputted to a display of a television receiver is extracted and the extracted high frequency component is amplified and added to the input image signal. This improves frequency characteristics of an image signal that is likely to be deteriorated while processed in individual circuits of the television receiver, thereby improving apparent image quality.
An example of a technique related to improvement in deterioration of image quality is a technique disclosed in Patent Literature 1. The technique disclosed in Patent Literature 1 is a technique for increasing a ratio of coding an image signal by using a spatio-temporal filter and an enhancer using linear operation.